Improvement in band sawing-machines



N UNITED STATES PATENT OFFICE. N

SEWALL K. LovEWELL AND LEVI L. LAMB, oF oHELsEA, MASS.

IMPROVEMENT IN BAND SAWING-MACHINES..

Specification forming part of Letters Patent No. 173,731., datedFebruary 22, 187 6; application filed May 15, 1875.

To all whom it mag/'concern Be it known that we, SEWALL KIMBALL LovEwELLand LEVI- LYsANDER LAMB,`both of Chelsea, in the county of Suffolk andState of Massachusetts, havewinvented an Improved Band SaWing-Machine;and we dohereby declare that the following, taken in connection with thedrawings which accompany and form part ot' this speciication, is adescription of our invention sufficient to enable'tliose skilled in theart to practice it.

The principal features in our invention cony sist in the peculiar mannerin which Awe always maintain an equal strain upon the saw.` blade,whether it is stationary and cool, or

whether it is in motion and heated. lo accomplish this resultwe placesprings in such' positions that, as the carrying-wheels are adjusted totighten the saw, the strain or pressure on the saw-blade compresses thesprings. When the saw is in motion and becomes heated, the springs relaxand take up the slackl occasioned lby the expansion of the saw-blade,always keeping it tight, while, as the blade contracts, the springs areagain compressed.

Another feature is, that we place the'lower guide for the saw-bladeverynear the working-surface of the table by grooving the under side ot'thc table, sliding the guide into said groove, and holding it firmly inplace by a thumb-screw. y

In the drawings which accompany and form a part of this specification,Figure 1 is4 a side elevation of an apparatus embodying our invention.Fig. 2 is a sectional elevation taken on the line a b, and Fig. 3 is asectional plan taken on the line c d.

A represents the frame; B C, the carryingwheels, and D the saw-blade. Erepresents the bearing for the arbor, pivoted at F, and verticallyadjusted by the screw G'. The bearing E is pivoted in the upright H,which is in the shape of a polygon, and extends down into the frame,being surrounded and held in position by Babbitt metal, as shown inFigs. 2 and 3. An opening is made through the frame at J, throughwhich'extcnds the piece K. The screw L is enlarged above this horizontalpiece K, so that as the screw is turned the upright and the horizontalpiece are drawn toward or forced away from each other at will. On theoutside ofthe frame are ears M, through which are passed rodsv N, saidrods being tapped into the horizontal piece K and surrounded by thespiral springs O.

To adjust a saw upon this machine it simply becomes necessary to placethe saw over the carrying-wheels, then turn the vertically-adjustingscrew, forcing the carrying-wheel upward until the springs O areslightly compressed, when the tension will be kept equal at all times.

It is evident that, While we have described I this apparatus as appliedto the upper carrying-wheel only,it may -be applied with equal facilityto the lower one also.

In order to get the lower guide asnear as possible to the work, therebylessening the tendency to bend and break the saw-blade, we groove thebed P, and place therein the guide Q, which, when in position, is heldtirmlyv l by the screw It.

We claimi .k 1. In a band sawing-machine,thecombination of the upright Hwith the vertically-adjusting screw L, horizontal piece K, rods N,

springs 0, and frame A, substantially as shown e

